It is known in bone surgery to frequently replace the natural sliding surfaces of joints with artificial sliding surfaces in cases of certain fractures or diseases relating to wear, e.g., arthrosis.
In the case of the human hip joint, the creation of an artificial acetabulum pan, which usually consists of plastic material, is independent of whether the femur head of the respective hip joint is essentially preserved and only provided with a shell prosthesis, or the femur head is radically removed and a suitable metal part which also has, inter alia, an artificial femur head, is substituted therefor.
The creation of artificial joint pans has the disadvantage that they must be fixed with bone cement after a cutting of the natural pan. Usually there must be used a considerable amount of bone cement, because the bone tissues often are not specially compatible with such bone cement, so that a formation of spongiosis and loosening of the hip pan can occur.
Therefore, it would be advantageous if such artificial joint pans could be fixed in a form-locking manner on the respective bone. Unfortunately, this has been impossible thus far, because it was not possible to exactly produce the respective recesses in the tissue. With respect to the exactness of such recesses, which are suitable and intended for holding artificial joint pans in a form-locking manner, relatively high demands must be made as to the accuracy of fit.
This difficulty was considered even greater, because such recesses grip the pan edge from behind in order to hold any projections of artificial joint pans, and must have a sufficiently large distance to the natural pan edge to keep the occurring loads sufficiently small.